Auto X Prize throws water on GM's 230 mpg claim, offers mpge calculator — Autoblog Green

Auto X Prize throws water on GM's 230 mpg claim, offers mpge calculator — Autoblog Green: "With all of the attention being paid to the 230 mpg number that the Chevy Volt will apparently be granted by the EPA, the Automotive X Prize thought it was time to weigh in on the subject of calculating fuel efficiency for vehicles that use energy sources other than gasoline. They don't like it. Instead, the AXP prefers MPGe, a 'rigorous and more neutral measure' of fuel efficiency. The AXP's John Shore walked us through how the long-running competition thinks about MPGe. They've been at it for a while.

First, let's define MPGe. MPGe stands for miles per gallon equivalent, and measures fuel economy based on the energy content of a gallon of petroleum-based gasoline. For those who like formulas, the AXP defines MPGe as (miles driven) / [(total energy of all fuels consumed)/(energy of one gallon of gasoline)]). Understanding and using MPGe is important, now more than ever, Shore said, because MPG is no longer particularly useful from the consumer's point of view. 'It is obsolete,' he said."